/**
 * The code was adapted from the "Rocksoft^tm Model CRC Algorithm".
 *
 * For more information on the Rocksoft^tm Model CRC Algorithm, see the
 * document titled "A Painless Guide to CRC Error Detection Algorithms"
 * by Ross Williams.
 */
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>


static const char *file_id="$Id: pmc-crc32.c 8 2013-01-03 18:22:38Z joymarquis@gmail.com $";

/* TODO: remove file id from this file */

unsigned int initial = 0xffffffff;
unsigned int xor_out = 0xffffffff;

/* For dynamically generate crc table */
#define POLY32 0x04c11db7

/* For quick self test */
unsigned char self_test_data[] = {
	0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
	0xfe, 0xdc, 0xba, 0x98, 0x76, 0x54, 0x32, 0x10,
};
unsigned int self_test_data_crc32 = 0xe91ee5fd;

/* statically allocated crc table */
unsigned int crc_tbl[] = {
	0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
	0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
	0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
	0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
	0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
	0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
	0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
	0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
	0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
	0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
	0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
	0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
	0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
	0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
	0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
	0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
	0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
	0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
	0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
	0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
	0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
	0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
	0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
	0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
	0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
	0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
	0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
	0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
	0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
	0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
	0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
	0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
	0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
	0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
	0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
	0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
	0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
	0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
	0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
	0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
	0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
	0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
	0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
	0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
	0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
	0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
	0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
	0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
	0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
	0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
	0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
	0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
	0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
	0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
	0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
	0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
	0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
	0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
	0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
	0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
	0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
	0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
	0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
	0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4,
};

void crc_tbl_calc(void)
{
	int i;
	unsigned int j;
	unsigned int r;

	for (j = 0; j < 256; j++) {
		r = j << 24;
		for (i = 0; i < 8; i++) {
			if (r & 0X80000000) {
				r = (r << 1) ^ POLY32;
			} else {
				r <<= 1;
			}
		}
		crc_tbl[j] = r;
	}

	return;
}

unsigned int crc32(unsigned int crc_initial, unsigned char *buf, int buf_len)
{
	unsigned int crc;
	int i;

	if (buf_len < 0) {	/* Assert if parameter error */
		fprintf(stderr, "Error: Incorrect buffer len\n");
		exit(1);
	}

	crc = crc_initial;
	i = 0;
	for (i = 0; i < buf_len; i++) {
		crc = crc_tbl[((crc >> 24) ^ (unsigned char)(buf[i] & 0xff)) & 0x000000ff] ^ (crc << 8);
	}

	return crc;
}

int main(int argc, char *argv[])
{
	int fd;
	int ret;
	char *fn;
	struct stat s;
	unsigned char *buf;
	int buf_len;
	unsigned int crc;

	if (argc != 2) {
		fprintf(stderr, "Usage: %s <binary_file_name>\n", argv[0]);
		fprintf(stderr, "\n");
		fprintf(stderr, "Calculate PMC crc32 from giving binary file\n");
		fprintf(stderr, "\n");
		fprintf(stderr, "    (Ver: %s)\n", file_id);
		return 1;
	}

	crc_tbl_calc();	/* Uncomment for dynamically generate crc_tbl */

	crc = crc32(initial, self_test_data, sizeof(self_test_data));
	crc = crc ^ xor_out;
	if (crc != self_test_data_crc32) {
		printf("Error: Self test failed, can not continue (%08x)\n", crc);
		return 1;
	}

	fn = argv[1];
	fd = open(fn, O_RDONLY);
	if (fd == -1) {
		printf("Error: open(%s)\n", fn);
		return 1;
	}

	ret = fstat(fd, &s);
	if (ret != 0) {
		printf("Error: fstat(%x)\n", fd);
		return 1;
	}

	buf_len = s.st_size;
	buf = malloc(buf_len);
	if (buf == NULL) {
		printf("Error: malloc(%d)\n", buf_len);
		return 1;
	}

	ret = read(fd, buf, buf_len);
	if (ret != buf_len) {
		printf("Error: read [req:%d, get:%d]\n", buf_len, ret);
		return 1;
	}

	crc = crc32(initial, buf, buf_len);
	crc = crc ^ xor_out;
	printf("%08x\n", crc);

	return 0;
}
